FRUIT DRY WEIGHT AND QUALITY OF 'BING' SWEET CHERRIES GROWN WITHOUT SOURCE LIMITATIONS

Understanding the seasonal pattern of potential fruit growth is important for identification and timing of possible management operations, and quantification of this pattern is an important prerequisite to serve as input for crop growth models. ‘Bing’ sweet cherry trees were heavily thinned at 63 degree-days (DD) (=8 days) after full bloom so weight and quality of the remaining fruit could be monitored under conditions of limiting and non-limiting carbohydrate supply. The effect of fruit thinning on mean shoot growth and trunk cross-sectional area also was analysed to detect possible translocation from reproductive to vegetative growth. Mean Fruit Dry Weight (MFDW) of tagged fruit was estimated weekly, based on fruit diameter, to identify the moment of the onset of competition between fruit within trees. At harvest, Fruit Number to Leaf Area Ratio (FNLAR, fruits m^-2 LA) was 52% lower in heavily-thinned trees than in non-thinned trees. Yield per tree was higher (P<0.05) in non-thinned trees, but MFDW and soluble solids content of mature fruit were higher (P<0.05) on thinned trees. No significant effects were observed on titratable acidity, firmness and vegetative growth. After 400 DD, differences in relative and absolute fruit growth rates between thinned and non-thinned trees were positive, resulting in a significantly higher MFDW on heavily thinned trees after 578 DD (61 days), which persisted until harvest. Therefore, if any operation to reduce source-limitation is carried out in commercial orchards, it should be done prior to 400 DD after bloom.